1. Field of the Invention
This invention relates to the form of a filter container with double construction for containing cartridge filters incorporated in a factory line for removing foreign particles mixed in liquid, and to the construction of a disposable unit container which integrally contains filtering material.
2. Description of the Related Prior Art
For the filtration of liquid such as paint or ink, there has generally been used a container containing one or more cylindrical cartridge filters and connected to the piping of the liquid to be cleaned. The liquid is forced to flow from the outside of the filter toward the inside thereof so that foreign particles or agglomerated particles are trapped. The accuracy of or the number of stages in the filtration is determined depending on the required level of the filtration. Therefore, in the manufacturing line of a plant, the combination of type and number of the cartridge filters in a unit container is varied in accordance with the object of the filtering and the necessary amount of the flow.
Since paint often includes hazardous pigments or organic solvents which are flammable and have an irritating odor, the housing has to be a sealed container which can withstand filtration pressure without leakage of the contents. If used for an extended period of time, filters may be clogged increasing the internal pressure in the housing to the control limit pressure, and necessitating replacement of the cartridge filters inside.
However, the factory line cannot be suspended for long merely for the replacement of filters. There has been proposed, as is disclosed in Japanese Utility Model Application Laid-open No. 37690/1989, a disposable filter container. It is not quite satisfactory from an economical standpoint to dispose of the container with mechanical intensity. With an aim toward eliminating the trouble of cleaning the inside of the housing at the time of the filter replacement operation, Japanese Utility Model Application Laid-open Nos. 163514/1989 and 174007/1989 propose enveloping the filters with a film during use that can be discarded after use together with the film, but this is not quite satisfactory, as there remain problems such as leakage of the liquid at the time of replacement and the mechanical intensity thereof.
The unit containers are consumables, and should be changed for new containers when one life thereof is completed. Since the unit containers are disposable as described above, the material thereof is generally a molded resin such as polypropylene or polyethylene. In this connection, there are problems such as size, accuracy and stability of the shape, and leakage of the liquid occurs easily due to the these problems.
In a manufacturing line for paint or ink, or a refining or conveyor line for fuel oil, a filter container containing one or more cartridge filters is connected to the line in order to trap and filter foreign particles or agglomerated particles mixed in the liquid. The accuracy of the filters and/or the number of stages of filtering are determined by the required level of the filtration.
Since the liquid to be filtered often includes toxic and hazardous organic solvents, the container (housing) for cartridge filters should be a pressure-resistant sealed container which withstands filtration pressure and which does not leak its contents. Moreover, the cartridge filters (filtering material) should be replaced with new ones if and when they have caught a certain amount of the foreign particles and their tissues are clogged and suspend the flow of the liquid. The replacement operation is usually conducted by suspending the production or conveyor line of the plant.
As mentioned above, the manufacturing line must be suspended to replace the filtering material, various inconveniences are caused, and countermeasures to solve the problems have long been sought. More particularly, when the manufacturing line is suspended at a plant for a liquid which contains highly viscous and polymeric substances such as paint and ink, the liquid is subjected to changes in its flowability when the residence time is too long. This will cause agglomeration of the liquid or changes in the product quality. Further, the replacement work itself is extremely dirty, cumbersome and heavy. Organic solvents, when evaporated, may cause hazards to the health of the operators, which is one of the reasons why it is difficult to keep young workers at jobs in the industry.
The above problem may be solved if an additional line is provided in parallel to the main manufacturing line so as to continue the production while replacing the filtering material in the main line. However, this requires additional equipment as well as additional space, and the measure would not solve the problem completely, because it is not effective in solving the second problem. As a means to solve the latter problem. Japanese Utility Model Application Laid-open No. 37690/1989 proposes disposable housings. However, it is not desirable from an economic standpoint to throw away structurally pressure-resistant housing.